Allow CSS library types

[janhancic]

If I have a thirdparty lib that only provides some CSS (a reset for instance). I'd like an easy way to get that CSS bundled anywhere in the app (aspect, workbench) without me having to explicitly include it somehow everywhere.

Best way to handle this is for my theme to say that it also wants this CSS from that library or something like that. I don't want to litter my app with "dummy" require calls to bring in CSS.

[andy-berry-dev]

Some initial thoughts (been discussing with @leggetter)

• @leggetter: "The reason it doesn't feel right is it's requiring a JavaScript library to include CSS"
• We could add a 'requireCss' that can be used in JS files - still doesnt feel right
• Link tags can be used - this doesnt work with the dependency mechanism
• Support @brjsLib 'some-css-lib syntax in themes to pull in a CSS library.
  • Where do CSS libs live? In 'libs' or in a seperate 'css-libs' dir?

I'm in favour of @brjsLib 'some-css-lib since it 'feels' right and keeps the CSS inclusion within CSS and doesn't leak across to JS.